1. Field of the Invention
The present invention relates to a method for controlling a compression system for the compression of a fluid medium.
2. The Prior Art
In industrialized countries, about 10% of the electric energy consumed by industry is spent on the production of compressed air. In addition, compressed air is a critical production factor, and consequently quality problems appearing in compressed air are in many cases economically much more significant than the energy spent on producing it. Ineffective use of compressed air has been found to be a significant problem in many countries.
In the compression systems of compressed air networks, compressors are used to produce compressed air, which is conducted via a cooler and a pressure tank into a secondary treatment apparatus, which is provided with filters and driers, and into a second pressure tank, from where the compressed air is supplied to the place of consumption. The compressors are controlled by means of controllers connected via a data communication bus to a control computer controlling the system. Connected to the computer are additionally e.g. pressure sensors, and the data obtained from these is used in the control of the system.
WO specification 91/06762 discloses a compressor control apparatus of this type, which can be connected to a computer. Via a data communication bus, several compressors can be connected to the computer. An individual controller can control the mode of operation of an individual compressor, said modes being on/off-line, modulating operation and deloaded operation. In WO specification 91/06762, each controller of the compressor can be controlled individually by means of signal obtained from a computer. In addition, the apparatus comprises a graphic display, such as a LED display, on which it is possible to present e.g. controller parameters, and the operator of the apparatus can operate it via a user interface by pressing different switches.
To save energy in the production of compressed air, various methods have been developed. Among the most typical solutions are standard controllers provided by compressor manufacturers and having their own control programs, which can not be customized to suit other manufacturers' compressors and which comprise no verification of efficiency of control. In addition, partly modular methods have been developed that are customizable for several compressor types and permit the connection of several pressure sensors. There are also measuring methods that can be used to ascertain the benefit regarding energy economy achieved by the control. However, these measuring methods are of a single-operation nature, and they have to be repeated at regular intervals if the aim is to ensure a continuous high quality of performance. The prices of customizable solutions are high due to the large amount of programming work needed, among other things. Under these circumstances, the equipments have to be built in small production series, and consequently they are expensive.
A large proportion, even 80% of maintenance visits associated with control systems are attributable to a misuse failure. This is because present control systems are separate systems that, after their introduction, are not maintained except sporadically. When users are changed out for new ones, the training they have once received is no longer useful. This leads to a situation where, in the course of time, even a well performing system does not necessarily answer its purpose.
The object of the present invention is to achieve a new type of control system in order to enable the operation of pneumatic systems and equivalent to be rendered more effective on a large scale at a reasonable cost and with limited personnel resources. The details of the features characteristic of the system of the invention are presented in the claims below.